Flame retardant compositions

ABSTRACT

The flame resistance of synthetic fibers and solid polymers are improved by treatment with a halogen containing amide having the formula ##STR1## wherein R is lower alkoxy; lower alkoxy carbonyl; ##STR2## X is chlorine or bromine; m is 0 or 1; n is 1-6; and y is 1-13.

This is a divisional of application Ser. No. 505,287, filed Sept. 12,1974, now U.S. Pat. No. 3,979,545.

BACKGROUND OF THE INVENTION

There is a great demand for fire retardant fibers. Cotton and rayonfibers, fabrics and garments probably compose the most flammable textilematerials in use today. Many of the synthetic fibers as well as fibersof animal origin are less flammable but the problem of imparting fireretardancy thereto still exists.

It is generally accepted that the earliest attempts to reduce theflammability of cellulose textiles was made by Wilde in 1753 in Englandand later by Gay-Lussac in France in 1821. Their studies revealed theutility of various inorganic salts as fire retardant agents forcellulose. The development of semi-durable and durable fire retardantfinishes began in the early 1900s but it was not until the 1950s thattruly durable finishes, i.e., resistant to ordinary laundering, wereavailable. The very early finishes were based on the precipitation ofmetal oxides within the fiber. Later developments included the discoverythat combinations of certain halogenated compounds and antimony oxideformed an efficient and moderately durable fire retardant for cellulose.

We have now discovered a group of halogenated compounds which can impartan effective degree of flame retardance to synthetic fibers and solidpolymers. In U.S. Pat. No. 3,644,493, there is described 2,3-dihaloalkylcompounds as flame retardant for various natural and synthetic fibers.All of these compounds are esters of allyl alcohol, which are thenhalogenated in contrast to the present compounds which are derivativesof allyl and diallyl amines and are, in fact, halogenated amides.

Accordingly, it is the object of this invention to provide a new groupof compounds for the imparting of flame resistance to synthetic fibers.This and other objects of the invention will become apparent from thefollowing detailed description of the invention.

SUMMARY OF THE INVENTION

This invention pertains to the imparting of flame resistance tosynthetic fibers and more particularly pertains to improving the flameresistance of synthetic fibers by treatment with a halogen containingamide compound.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The compounds employed in the present invention are halogen containingamides of the formula ##STR3## In the foregoing formula, R can be loweralkoxy, i.e., of 1-6 carbon atoms; lower alkoxy carbonyl; ##STR4## X canbe chlorine or bromine; m can be 0 or 1; n can be 1-6; and y can be1-13.

Illustrative of lower alkoxy groups which can be R in the foregoingformula are methoxy, ethoxy, propoxy, etc. Bis(β,γ-dibromopropyl) ethylcarbamate, ##STR5## is exemplary of such compounds.

In those compounds where R is lower alkoxy carbonyl, i.e., ##STR6## thelower alkyl moiety (A) contains 1-6 carbon atoms. Methoxy carbonyl,ethoxy carbonyl, propoxy carbonyl, etc. are illustrative of suchradicals and N,N-bis(β,γ-dibromopropyl) ethyl oxamate, ##STR7## isexemplary of the resulting compounds.

In the compounds in which R is represented by the group ##STR8## thenumber of carbon atoms is, as before, 1-6 and the halogen can bechlorine or bromine. N,N-bis(β,γ-dibromopropyl)amino is illustrative ofsuch a radical and tetra(β, γ-dibromopropyl)urea, ##STR9## isillustrative of the resulting compound. Where R is represented by thethe group ##STR10## the lower alkyl and halogen groups are as describedabove and the arylene is phenylene. Illustrative of such a compound isN,N,N',N'-tetrakis(β,γ-dibromopropyl)isophthalamide, ##STR11##

In the compounds in which R is represented by the group ##STR12## thelower alkyl and halogen are as described above. N-(dibromopropyl) amidois illustrative of such a radical and N,N'-bis(β,γ-dibromopropyl)oxamide, ##STR13## is exemplary of the resulting compound.

The compounds employed in the present invention are known and can beprepared by conventional means.

The foregoing halogen containing amides are employed in solution form orin the form of an aqueous emulsion. In either case, the amides can varyin concentration over a wide range of from about 5-25 weight percent andpreferably about 10-20 weight percent.

Suitable solvents for the halogen containing amides include thehalogenated hydrocarbons such as trichloroethylene, perchloroethylene,methylene chloride, and the like; ketones such as acetone, methyl ethylketone, and the like; ether, and any other organic solvents in which thehalogen containing amides are soluble.

Suitable emulsifying agents for maintaining the amides in aqueousemulsions include anionic, cationic and non-ionic dispersing agents orsurfactants. Suitable non-ionic surfactants include the alkyl phenoxypoly(ethyleneoxy)ethanols, and the dialkyl phenoxypoly(ethyleneoxy)ethanols, preferably those wherein the alkylsubstituents have 5-12 carbon atoms and which have 1-20 ethyleneoxygroups. Typical members are octyl phenoxy poly(ethyleneoxy)ethanol,nonyl phenoxy poly(ethyleneoxy)ethanol and dodecyl phenoxypoly(ethyleneoxy)ethanol. Also useful are the fatty acid esters ofpolyhydric alcohols or ether alcohols such as glycerol monostearate;esters of ethylene glycol, diethylene glycol, triethylene glycol andpolyethylene glycol such as the condensation product of oleic acid withethylene oxide; and fatty esters of sugar alcohols. Suitable anionicsurfactants include the alkali metal alkyl benzene sulfonates such assodium and potassium dodecyl benzene sulfonate; the alkali metal alkylsulfates such as sodium lauryl sulfate; the sulfonated aliphaticpolyesters, free acids of complex phosphate esters, sodium salts ofcomplex phosphate esters and sodium salts of disproportionated woodresin. Suitable cationic surfactants include the fatty amides ofmonoethanol amines, fatty nitriles and fatty acid amides such as oleinmorpholide. Also useful as cationic agents are the polyoxy ethylatedalkyl amines.

The synthetic fibers which can be treated in accordance with the presentinvention include the polyamides such as 6-, and 6,6-nylons, polyesters,polyolefins such as polypropylene or polyethylene, acrylics, triacetatessuch as arnel, and blends of natural and synthetic fibers such ascotton/polyester and wool/polyester. Mixed fabrics and fibers may besimilarly treated.

The fibers may be in any of the usual forms and in natural bulk,interwoven, knitted or felted form as for example in the form of astaple fiber or continuous filament in bulk form, or in the form of tow,rope, yarns, slubblings, warps, fabrics and felts and the like, andtreated as a wound package, running length, fiber stock, bulk, etc.

The fire retardant compounds of the instant invention can be applied tothe synthetic textile fibers by a variety of procedures and usingdifferent kinds of equipment. While the individual steps and equipmentcan vary with the different procedures, in each case, the fiber isimmersed in the solution or emulsion and the compound is depositedtherefrom as, for example, by removing the solvent by evaporation orvaporization. In one suitable procedure, a multitude of synthetictextile yarn ends from a creel are passed through a container in whichis found the solution of the halogen containing amide. Thereafter theyarn ends are passed between squeeze rolls to remove excess solution andthen passed over a multitude of drying cans which are usually maintainedat a temperature of about 150°-230° F. Similarly, the fibers can betreated by dipping them into the solution or emulsion, followed bydrying.

The temperature at which the fibers are immersed in the solution oremulsion can vary over a wide range of from about 30°-100° C.;preferably the temperature is about 90°-100° C. and most preferablyambient temperature is employed. The immersion time can similarly varyover a wide range of from about 1/4-2 hours, preferably about one-halfhour. The fibers are maintained immersed in the solution or emulsionuntil an effective flame resistant amount of the halogen containingamide, generally about 5-20 weight percent, and preferably about 10-15weight percent of the dried impregnated fibers, has been picked up bythe fibers. The halogen containing compounds of this invention can alsobe used to impart flame resistance to solid thermoplastic polymers suchas polyethylene, polypropylene, polyesters and copolymers and blendsthereof, nylons, polyurethanes, etc. If desired, about 5-20% of anantimony compound such as Sb₂ O₃ is used in conjunction with the halogencontaining compound to achieve a higher degree of flame resistance inthese solid thermoplastic polymers.

The flame resistant solid thermoplastic polymer compositions may beprepared by utilizing conventional methods such as internal mixers suchas Banbury, continuous mixers, mixing extruders, and two-roll mills.

The following Examples are set forth in order to further illustrate thepresent invention. Throughout this specification and claims, alltemperatures are in degrees centigrade and all parts and percentages areby weight unless otherwise specified.

EXAMPLE 1

Bis(β,γ-dibromopropyl)ethylcarbamate was prepared by the bromination ofN,N-(diallyl)ethylcarbamate as follows.

Charged into a one liter, 3-necked flask equipped with the necessaryadjuncts were diallylamine, 48.6 g (0.5 mole), triethylamine, 50.6 g(0.5 mole) and 200 ml of ether. This was cooled to 0° C. andethylchloroformate, 54.3 g (0.5 mole) was added slowly dropwise withconstant stirring. The addition took 31/2 hours, maintaining atemperature of 0° C. An additional 350 ml of ether was added to maintainfluidity. After warming to room temperature, the solid amine salt wasfiltered and the ether distilled from the filtrate. The resultingproduct was purified by distillation under reduced pressure. B.P.40.5°-41° C. at 0.1 mm Hg. - Yield 71%.

Charged into a one liter, 3-necked flask equipped with a stirrer, N₂inlet, thermometer, dropping funnel and condenser wereN,N-diallylethylcarbamate, 57.8 g (0.342 mole), and 300 ml ofchloroform. This was cooled to 0° C. and with vigorous stirring,bromine, 109.3 g (0.684 mole) was added dropwise. When the addition wascomplete, the bath was warmed to room temperature and allowed to standovernight. The chloroform was then distilled and finished at 0.5 mmpressure. Yield 81.2%.

A sample was submitted for mass spectra which showed a compound of mass485 containing 4 bromines. This confirms the structure of the compound.

Bis(β,γ-dibromopropyl)ethylcarbamate (40 g ) is dispersed in ethyleneglycol (80 g) using as emulsifier, Duponal OS (2 g) an amine long chainalcohol sulfate. The mixture is heated with stirring until a homogeneousdispersion is obtained. The solution is then cooled to room temperature.Before use, this dispersion is emulsified with water (150 g) preferablyusing a colloid mill.

EXAMPLE 2

N,N-bis(β,γ-dibromopropyl)ethyloxyamate was prepared by the brominationof N,N-diallylethyl oxamate as follows.

Ethyloxalate, 146.1 g (1.0 mole), was charged into a 3-necked flaskequipped with a mechanical stirrer, dropping funnel, condenser anddrying tube. Diallylamine, 97.2 g (1.0 mole) was slowly added withconstant stirring. There was a moderate exotherm during the additionuntil approximately one-half the amine was added, at which time thetemperature declined. When the addition was complete, the bath washeated to 80 °-90° C. for 4 hours and then cooled by standing overnight.

The product was then fractionated and vacuum distilled and the portionboiling at 105°-106° C. at 1 mm Hg was collected. The product wassubmitted for mass spectra determination which showed a mass of 197 andthe expected fragments of the desired product, N,N-diallylethyloxamate.

The N,N-diallylethyloxamate, 77.3 g (0.39 mole), dissolved in 100 ml ofchloroform, was charged to a one liter, 3-necked flask equipped with astirrer, thermometer, dropping funnel, condenser and drying tube. Thesolution was cooled to 4° C. and bromine, 124.7 g (0.78 mole), wasslowly added. When all the bromine was added, the chloroform wasdistilled at atmospheric pressure. The remaining chloroform was removedunder reduced pressure (water pump). The residue was taken up inbenzene, filtered and evaporated under a stream of N₂. M.P. 160° C.(with decomposition). Mass spectra analysis confirmed the desiredcompound.

N,N-bis(β,γ-dibromopropyl)ethyloxamate (30 g) is dissolved inperchloroethylene (180 ml) using Triton X-100 (5 g) which is anoctylphenoxypolyethoxy ethanol.

EXAMPLE 3

Tetra(β,γ-dibromopropyl)urea was prepared by the bromination ofbis(diallyl)urea as follows.

Charged under dry N₂ to a one liter, 3-necked flask equipped as in theprevious preparation, were diallylamine, 44.3 g (0.456 mole) andtriethylamine, 46.1 g (0.456 mole), in 100 ml of dry benzene. This wascooled with stirring to 0° C. and to this was carefully added phosgenein benzene, 237.8 g (0.228 mole). The pot temperature was maintained at0°-5° C. by the regulation of addition rate. When the addition wascomplete, the amine hydrochloride was filtered off, the benzene washedwith H₂ O and dried. The benzene was then removed under reducedpressure. Yield - 41.3 g 82%-83% theory. Mass spectra confirmed theexpected structure.

Bromination of bis(diallyl)urea was effected as follows: charged into adry one liter, 3-necked flask with the usual equipment werebis(diallyl)urea, 39.4 g (0.18 mole), and 100 ml chloroform. This wascooled to 0° C. with constant stirring. Then, 115.1 g (0.72 mole)bromine in 50 ml of chloroform was slowly added, maintaining atemperature of 0°-5° C. Additional amounts of chloroform (total 150 ml)were added to keep the reaction mixture fluid. When the addition wascomplete, the batch was stirred for one-half hour until it reached roomtemperature. The solvent was distilled. The residue consisted of a thicksyrup which set up to an amorphous solid.

Tetra(β,γ-dibromopropyl)urea (25 g) was dissolved in 100 ml ofperchloroethylene using as emulsifying agent, Triton X-100.

EXAMPLE 4

N,N,N',N'-tetrakis(β,γ-dibromopropyl)isophthalamide was prepared by thebromination of tetraallylisophthalamide. This latter compound wasprepared as follows.

Charged, under dry N₂ to a one liter, 3-necked flask equipped with astirrer, N₂ inlet, thermometer, dropping funnel and condenser, werediallylamine, 88.6 g (0.912 mole), and triethylamine, 92.3 g (0.912mole), in 300 ml of ether. Isophthaloyl chloride, 92.5 g (0.456 mole),dissolved in 200 ml of ether, was slowly added maintaining a temperatureof approximately 0°-5° C. Addition was complete in 31/2 hours.Evaporation of the ether yielded 129.6 g of product - 87.5% of theory.

Bromination of the bis amide was accomplished as follows: charged underdry nitrogen to a one liter, 3-necked flask equipped with a stirrer, N₂inlet, dropping funnel and condenser was tetraallylisophthalamide, 123.8g (0.38 mole) and 200 ml of chloroform. This was cooled with stirring to0° C. and there was slowly added bromine, 243.0 g (1.52 mole), dilutedwith chloroform. The temperature was kept at -5° to 5° C. The productbegan to separate out and more solvent was added. When the addition wascompleted, the batch was stirred at room temperature for 1 hour. Themixture was then heated to remove solvent. There remained a thick syrupwhich set up to an amorphous fluid.

N,N,N',N'-tetrakis(β,γ-dibromopropyl)isophthalamide (30 g) is emulsifiedin water using IGEPAL CA-420 (5 g) anoctylphenoxypoly(ethyleneoxy)ethanol. Emulsification is hastened by useof heat and ultrasonic vibration.

EXAMPLE 5

N,N'-bis(β,γ-dibromopropyl)oxamide was prepared by the bromination ofN,N'-bis(allyl)oxamide. The latter compound was prepared as follows:

Charged to a 2-liter, 3-necked flask were allylamine, 114.2 g (2.0 mole)and 150 ml of ethanol. To this solution, ethyl oxalate, 146 g (1.0 mole)in 50 ml of ethanol was slowly added with stirring. The reaction wasexothermic and when the temperature reached 40° C., cooling was appliedto 20°-+° C. at which temperature the remaining ethanol was added. Themixture was cooled to room temperature and allowed to stand overnight.The batch was further cooled in ice and filtered and the filter cakewashed with ethanol and air dried. Yield - 123.7 g, M.P. 156.5°-157.5°C.

The bromination was carried out in the usual manner using glacial aceticacid as the solvent. The yield was 102.1 g (83.5% of theory), M.P.222°-224° C. Mass spectra confirmed the structure in both molecularweight and bromine content.

N,N'-bis(β,γ-dibromopropyl)oxamide (30 g) is dissolved in 110 ml ofperchloroethylene using IGEPAL CA-420 (5 g).

EXAMPLE 6

The compound bis(β,γ-dibromopropyl)ethylcarbamate is most readilyapplied to a fabric material by exhaustion from an aqueous system. Thesolution is prepared as shown in Example 1. A cloth of polyester isplaced in the bath which is then heated to 90°-100° C. A polyestersoftener such as sorbitol, sulfonated castor oil, low molecular weightpolyethylene or silicone textile lubricants, may be added. Theabsorption of the carbamate by the fibers is low at low heat and high athigher temperatures. The fabric is kept submerged for 1-2 hours, afterwhich the fabric is removed and dried in an air circulating oven at100°-110° C. The cloth is weighed to determine the add on, usually 5% to10% increase is sufficient to render the fabric flame retardant. Thepick-up can be regulated to yield the desired degree of flameretardance.

EXAMPLE 7

A weighed nylon 6,6 cloth is submerged in the solution prepared inExample 2 and soaked for about 15-20 minutes. The cloth is then dried inan air circulating type oven and weighed for total pick-up. 7% was theamount of pick-up on weight of goods (O.W.G.). The cloth, when heldvertically, would not support combustion when the source of flame wasremoved.

EXAMPLE 8

Example 7 was repeated except that the flame retardant compound istetra(β,γ-dibromopropyl)urea and the fabric used is cellulosetriacetate. The treated fabric is rendered flame retardant as measuredby the vertical flame test.

EXAMPLE 9

The solution prepared in Example 4 usingN,N,N',N'-tetrakis(β,γ-dibromopropyl)isophthalamide may be useddirectly. A polyester cloth is placed in the solution which is heated toboiling for 1 hour. The solution is cooled (or optionally, the cloth maybe removed when hot) and dried at 100° C. in an air circulating oven.Over 6% O.W.G. pick-up imparts flame retardance as measured by verticalflame test.

EXAMPLE 10

A solution of N,N'-bis(β,γ-dibromopropyl)oxamide in perchloroethylene(prepared in Example 5) is used. A piece of nylon cloth is soaked in thesolution for about 20 minutes. The cloth is oven dried using aircirculation and weighed. The pick-up (O.W.G.) is about 8%. The clothpasses the vertical flame test and untreated cloth burns.

various changes and modifications can be made in the process andproducts of this invention without departing from the spirit and thescope thereof. The various embodiments set forth herein were for thepurpose of further illustrating the invention but were not intended tolimit it.

We claim:
 1. A halogen containing amide of the formula ##STR14## whereinR is lower alkoxy,lower alkoxy carbonyl,

    +N(C.sub.n H.sub.2n+1-y X.sub.y).sub.2, ##STR15## X is chlorine or bromine; m is 0 or 1;

n is 1-6; y is 1-13; andwhen R is lower alkoxy and n is 1 and m is 0, yis 2-3.
 2. The amide of claim 1 wherein the lower alkoxy radicalcontains 1-6 carbon atoms and the lower alkoxy carbonyl radical contains2-7 carbon atoms.
 3. The amide of claim 2 wherein said amide isN,N-bis(β,γ-dibromopropyl)ethyloxamate.
 4. The amide of claim 2 whereinsaid amide is bis(β,γ-dibromopropyl) ethyl carbamate.
 5. The amide ofclaim 2 wherein said amide is tetra(β,γ-dibromopropyl)urea.
 6. The amideof claim 2 wherein said amide is N, N, N¹, N¹ - tetrakis (β,γ-dibromopropyl) isophthalamide.
 7. The amide of claim 2 wherein saidamide is N,N,'-bis(β, γ-dibromopropyl)oxamide.